Web-DSS-Chapter-03

SECTION 3.22 ■ Exercises 73
7. “Electronic commerce” is one of the most common
terms in the business world. It is the buying
and selling of goods and services on the Internet.
One of the most popular products in e-commerce,
as it is more commonly known, is the compact
disc. This exercise describes the database of a CD
warehouse.
The company’s customers and employees
access the database. Assume that customers have
access to a company’s Web site and that they are
able to open an account by providing their social
security number, name, address, and music preferences.
For each employee, the following information
is recorded: an employee identification
number, a name, an address, a birth date, and the
title of the position within the company.
The products for the CD warehouse are the
albums. The database records the following information
about each album: an album identification
number, the name, the group name, the
musical category, the name of the vocalist, the
names of the other band members, and the number
of CDs in stock. The database also keeps the
following information about suppliers: a supplier
identification number, the address, the name of
the company, and the name of the contact
person.
An album may be bought by one or more
customers, and one customer may buy one or
more albums. Additionally, an employee may
monitor one or more albums; however, an album
is monitored by exactly one employee. Suppliers
may provide one or more albums; however, an
album is supplied by exactly one supplier. Using
the above information, draw an E-R diagram for
the CD warehouse database. Identify the relationship
cardinalities and the key attribute of each
entity.
8. One of the three-star hotels in the Miami area is
in the process of updating its database. The hotel
has various room types on each of its floors. The
rooms may be regular, deluxe, or a suite and each
can be either a single, double, or triple. The suites
have ocean views and are bigger than the regular
rooms. The deluxe rooms are as big as suites, but
they do not have an ocean view. All the rooms
have air conditioning. Most of the rooms are
non-smoking, but the hotel offers some smoking
rooms as well. Each floor has a different number
of a particular room type. The price of each room
differs by the size of the room, the view, and the
room’s location (first floor, second floor, etc.).
The customers are charged on a per-day
basis. The number of days is computed based on
the check-in time and the check-out time. The
following details are stored for each customer:
name, address, check-in date, check-out date,
payment method, and final bill amount. In addition
to the room charges, there may be extra fees,
such as telephone usage, fax services, extra beds,
and room service. For this application, we assume
that a room can be booked by more than
one customer as long as there is no overlap and
that a customer can be assigned to any available
room. Draw an E-R diagram for the hotel database
and state any assumptions made in order to
develop a complete diagram.
9. The Newark divisional office of the Life Insurance
Corporation of America stores all the necessary
information about its policyholders in a
database. A policyholder pays a premium until
the maturity of the policy or until his or her
death, at which time the sum assured and the
bonus are paid to the beneficiary. The premium
to be paid is determined based on the age of the
person proposed and the term of the policy. The
Newark division records the following information
about each policyholder: social security
number, name, address, date of birth, maturity
amount, and annual premium.
The corporation has divided its Newark
division into 15 zones for its convenience. For
each zone, they store the Zone ID and the location.
Each zone also has a manager. Every zone
has a number of agents allotted, typically ranging
from 10 to 20 and every agent must procure a
minimum of 10 customers. Each policyholder in
a particular zone is assigned to only one agent
affiliated with that zone; this agent puts forth the
terms of the policy. Additionally, an agent in a
particular zone can serve multiple policyholders.
Make assumptions for the remaining relationships
and draw an E-R diagram for the corporation’s
database.
10. Ford distribution centers provide automotive
parts to authorized dealers. The dealers then
distribute the parts to customers throughout
North America. Ford is under pressure to provide
excellent customer service at a minimum
cost. Maintaining a well-organized database of